You can drill down to see more detail in a dimension. 

For example, if you right-click a category label (row heading) for a dimension with others collapsed beneath it, you can choose to drill down and only see data for that category. When a dimension is drilled, you do not see the category labels for that dimension displayed on the grid, since only the records for a single category value are being displayed. If you have a decision pivot on the form, it displays category values and lets you change to other values if you want. 

To drill down into a dimension,

• Right-click a category label and choose Drill In To This Value, or
• Right-click a pivot button and choose Drilled In.

• Right-click the corresponding pivot button or,
• Right-click the decision grid in the upper-left corner and select the dimension.